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Use of Streptomyces spp. as biocontrol agents of wheat crown rot caused by fusaria

Elena Maria Colombo: DeFENS, Università degli Studi di Milano

<div>Crown rot of wheat is caused mainly by <em>Fusarium</em> species and in specific climatic conditions can reduce production up to 50-90%. Biocontrol methods are an interesting approach to satisfy the increasing demand for alternatives to chemical fungicides. <em>Streptomyces</em> spp. act as growth promoters as well as biocontrol agents. Therefore, they are promising candidates for seed treatments, which combine their ability to produce a wide range of biologically active molecules with the potential to establish tight interactions with plants. Forty-seven <em>Streptomyces</em> spp. strains were selected among 1500, isolated from roots or rhizosphere of various crops. Their ability to reduce mycelial growth (up to 80%) of five <em>Fusarium graminearum</em> and <em>F. culmorum</em> strains (<em>N</em>=5), representing geographical, genotypic and toxigenic diversity, was determined <em>in vitro</em>. Streptomycetes showing inhibition >20% were further tested <em>in vitro</em> on wheat seedlings (cv. Bandera) for their ability to reduce disease symptoms. The root-necrosis was reduced up to 50% after 4 dpi. Moreover, the strains reduced the severity of crown rot up to 80% after 6 dpi in comparison to the untreated control. The selected strains did not inhibit the growth of the seedlings at the tested condition. Further <em>in vivo </em>studies are foreseen to assess their plant growth promoting ability. Until now, our results confirm that streptomycetes are a promising source for developing organic seed treatments.</div>